It has been estimated that 7 million Americans suffer from progressive gastroesophageal reflux disease (GERD) which is characterized by frequent episodes of heartburn, typically on at least a daily basis. Without adequate treatment, GERD can cause erosion of the esophageal lining as the lower esophageal sphincter (LES), a segment of smooth muscle located at the junction of the stomach and the esophagus, gradually loses its ability to function as the barrier that prevents stomach acid reflux.
While drug therapies, such as proton pump inhibitors, have become a viable option for many of those diagnosed with GERD, surgical treatment may be indicated for patients with more serious disease or those who do not wish to adhere to daily, potentially expensive drug regimes that keep the disease under control. One such surgical approach is the Nissen Fundoplication which involves wrapping a portion of the stomach around the LES for support, then suturing it into place. Obviously, this invasive open surgical procedure is indicated only for patients who do not respond to standard GERD medications or dietary changes.
More recently, less-invasive endoscopic surgical procedures have been developed to restore compliance to the LES. The first is a type of endoluminal gastroplication utilizing the Bard EndoCinch™ Endoscopic Suturing System (C. R. Bard, Inc., Billerica, Mass.) which involves a endoscopic apparatus that places a series of adjacent sutures in LES to form one or more pleats that improve the ability of the sphincter to restrict the back flow of acid into the esophagus. Modest improvement of LES function has been demonstrated, but at least one study found that overall the number of reflux incidents was unchanged and the improvement in gastroesophageal reflux (GER) was modest. The data suggests that the plications eventually begin to fail and are not able to create a permanent fusion between the gastric folds, thus reducing the effectiveness of the treatment over time. A second surgical option involves the use of radio-frequency energy to reduce patient symptoms associated with GERD. The Stretta® System (Curon Medical, Inc., Sunnyvale, Calif.) comprises a flexible catheter with needle electrodes and a control module which are used to create thermal lesions or scarring at the LES. Unlike endoplication treatment, which is most effective at reducing acid exposure when upright, the RF scarring acts to reduce supine acid exposure in treated patients. It is thought that neurolysis within the treated area acts to reduce acid sensitivity and disruption of the vagal mechanosensitive trigger that leads to GERD. It is this loss of sensitivity that is most likely responsible for symptom relief as little reduction in the pH profile has been found. Furthermore, many patients require more than one treatment to achieve positive results. Laser ablation has also been studied in an animal model as a means to achieve scarring, but only moderate elevation of LES yield pressures was noted.
Another approach to treat GERD has been to inject or implant materials into the LES to bulk up and tighten the sphincter, thereby improving its functionality as a barrier to acid reflux. Collagen, PTFE paste, and plexiglass materials have been injected in human patients for LES augmentation, but studies have shown the benefits to generally decrease over time, requiring follow up treatments. One commercially available treatment, the Enteryx® Procedure (Boston Scientific Corp., Natwick, Mass.) involves the injection of an ethylene vinyl alcohol polymer (EVOH) in a dimethyl sulfoxide carrier within and along the muscle layer of the LES. As a foreign body, the injected polymer eventually becomes encapsulated by a fibrotic layer. Improvement in LES function is due to a decrease in muscle distensibility and increase in yield pressures. However, questions have arisen as to the safety of EVOH injections for treating GERD following the early clinical experience and the product was removed from the market in 2005. A similar system is the GATEKEEPER™ Reflux Repair System (Medtronic Inc., Minneapolis, Minn.) which involves endoscopically implanting a series of dry pellet-like prostheses made of a hydrogel, similar to that used to make contact lenses. Once implanted in tissue, the material gradually swells to about the size of a gelcap and exerts pressure on surrounding tissues, thereby bulking the LES and improving its integrity. A disadvantage of the aforementioned injectable/implantable materials is their complete lack of radiopacity makes it difficult to confirm correct placement under fluoroscopy, if so desired.
Despite progress being made in finding a efficacious endoscopic therapy for the treatment of GERD, a commercially available solution which has been demonstrated to be both safe and effective over the long term has, so far, proven to be elusive. The limitation of these procedures need to be addressed in a procedure that provides true, long-term augmentation of the LES that reduces patient GERD symptoms and decreases esophageal acid exposure.